Allow installing RDoc from a git source

Co-authored-by: Vinicius Stock <vinistock@users.noreply.github.com>

Author: st0012

Diff for: Rakefile

@@ -88,8 +88,18 @@ parsed_files = PARSER_FILES.map do |parser_file|
 end
 
 task "#{path}.gem" => package_parser_files
-desc "Generate all files used racc and kpeg"
-task :generate => parsed_files
+
+desc "Generate all files use racc and kpeg"
+task :generate do
+  unless ENV.key?('BUNDLE_GEMFILE')
+    Gem.install 'racc', '> 1.4.10'
+    Gem.install 'kpeg', '>= 1.3.3'
+  end
+
+  parsed_files.each do |file_name|
+    Rake::Task[file_name].invoke
+  end
+end
 
 task :clean do
   parsed_files.each do |path|

Diff for: ext/rdoc/extconf.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+# Generate all parse files using racc and kpeg. This is not necessary for regular gem installation, but it is when
+# installing RDoc from the git source. Without this, the generated parse files would not exist and RDoc would not work
+system("rake generate") if Dir.exist?(File.join("..", "..", ".git"))
+
+# RDoc doesn't actually have a native extension, but a Makefile needs to exist in order to successfully install the gem
+require "mkmf"
+create_makefile("rdoc/rdoc")

Diff for: rdoc.gemspec

@@ -35,6 +35,7 @@ RDoc includes the +rdoc+ and +ri+ tools for generating and displaying documentat
   s.bindir = "exe"
   s.executables = ["rdoc", "ri"]
   s.require_paths = ["lib"]
+  s.extensions = ["ext/rdoc/extconf.rb"]
   # for ruby core repository. It was generated by
   # `git ls-files -z`.split("\x0").each {|f| puts "    #{f.dump}," unless f.start_with?(*%W[test/ spec/ features/ .]) }
   non_lib_files = [